The integrated photonics concept is the application of thin-film technology to optical circuits and devices for the purpose of achieving efficient, high-performance, and economical optical systems. Photons are guided on a planar chip by integrated photonic waveguides. The field can be viewed as the optical equivalent of microelectronics for integrated circuits. It concerns the physics of light waves in thin films, materials and losses, light coupling, and nonlinear interactions in waveguide structures. In addition to its inherent compactness, stability, and reproducibility, a primary advantage is the optical confinement of the guided-waves which yield high electric fields at low absolute power levels.
Driven by the communication bottleneck in very-large-scale integration (VLSI) electronics, significant momentum in silicon photonics has recently occurred, yielding a potential explosion of applications in sensors, optical interconnects, integrated microsystems, and computing. Integrated optics in silicon is particularly attractive because it is compatible with well-developed and cost-efficient complementary metal-oxide-semiconductor (CMOS) technology and can be integrated with electronic devices monolithically. For operation at 1.55 μm wavelength, single-mode silicon strip waveguides surrounded by a silicon dioxide cladding have submicrometer cross sections of typically 450 nm by 250 nm due to the high contrast between the refractive indices of silicon (3.48) and silicon dioxide (1.44). Highly confined optical modes allow for densely integrated waveguides and small radius of curvature waveguide bends. Key components have been demonstrated in silicon including optically pumped lasers, dense optical waveguide interconnects, compact filters, low power switches, and high-speed electrical-to-optical and optical-to-electrical converters.
Conventional demonstrations of photoluminescence (PL) and electroluminescence (EL) in silicon (Si) have involved a wide variety of dopants in Si including Er/Si-nanoclusters, optically active hydrogen (H) defects caused by ion implantation or plasma treatment, Y—Er disilicate films, dislocation loops due to B doping, C doping, and ion implantation of Si self-interstitials. Of these demonstrations, only H defects from surface plasma treatment have demonstrated room temperature EL in the 1550 nm telecommunications wavelength range while operating near CMOS-compatible voltages. Other demonstrations of EL in Si emit at shorter wavelengths (less than 1200 nm), emit only at cryogenic temperatures, or require bias voltages of 50 V or larger for measurable emission. In other words, these other demonstrations of electrically driven light emission in silicon are not feasible for use in integrated optical systems.